Currently, various methods are employed to compress the content of computer system main memories such as Random Access Memory (RAM). These methods decrease the amount of physical memory space needed to provide the same performance. For instance, if a memory is compressed using a 2:1 ratio, the memory may store twice the amount of data at the same cost, or the same amount of data at half the cost.
One such method is Memory Expansion Technology (MXT), developed by International Business Machines (IBM) of Armonk, N.Y. MXT addresses system memory costs with a memory system architecture that doubles the effective capacity of the installed main memory. Logic-intensive compressor and decompressor hardware engines provide the means to simultaneously compress and decompress data as it is moved between the shared cache and the main memory. The compressor encodes data blocks into as compact a result as the algorithm permits.
However, there is currently no method for compressing data that is stored in a cache. Having the capability to compress cache data would result in similar advantages as main memory compression (e.g., decreasing the amount of cache space needed to provide the same performance).